Process for the extraction of copper and nickel, particularly from lowgrade ores and products.



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' PBDGESSFOB THE EXTRACTION OF COPPER AND NICKEL, PARTICULARLY FROM IM'D'W GRADE GEES AND PRODUCTS.

1,043,291, g No Drawing. Application filed February 6, 1912. Serial No. 675,831.

To all whom aitma'y concern:

Be it known thatwe, WILHELM Bononnns, professor, a subject of the GermanEmperor,

' and resident of Ludwigsallee, Aachen,

dent of Trondhjem,

I Germany, and Pnonnsnn, en

a subject of the Kin of Norway, an resiorway, have invented certain new and useful Improvements in Processes for the Extraction of Copper and Nickel, particularly fi'om low-grade Ore and products; and we do hereby declare the following to be a full, clear, and exact description of the inventiomsuoh as will enable others skilled in the art to which it appertains to make and use the. same.

The processes heretofore known for the treatment of nickel ores containing copper aim either to concentrate the ores by a rather complicated system of matte smelting combined with wet lixiviation and precipitating processes, or to roast the ore so that chiefly its cop er and cobalt contents are turned into so fates and leached from the residue containin the nickel, which may then be reduced li e a pure nickel ore. The latter process may be suitable for ores containing paying amounts of cobalt besides copper and nickel, but it has not given much satisfaction with ores from which copper alone has to be separated from nickel. A complete recovery and a perfect separation of the .twometals especially when low grade ores are to be treated, was heretofore one of the most troublesome metallurgical problems, until the inventors of the present process concluded to altogether abandon the workin rinciples just referred to in favor of the oilow'ing idea.

According to this invention no separation of copper and nickel should be attempted during the first stages of treating the ore consisting of matte smelting, roasting and leaching and the diflioulty of ex traoting the nickel down to the last traces from the roasted matte should be overcome by using the residue from leaching the roasted matte as a flux in the first stage of the process: 2'. e.,',in the matte smelting. These principles combined will allow an almost complete recovery of .both metals copper and nickel.-

The whole process will be fully understood by the following explanations of the single. stages:

Specification 0t Letters Patent.

Patented-Nov. 1 912,

First. The ore is smelted referably in an electric furnace. Unless t e gangue of the ore is readily fusible, a flux .must be fadded, the nature of which determined by the nature ofthe gangue. cases the gangue consists of silicates icon much silica, a basic flux like-Ilestelie will be advisable. This flux be As inmost added in small quantities, in order to leave the amount of silica high enough to form a slag of the chemical character of approximately a bisilicate. Thus in the smelting o erat-ion a crude matte containing practioally all the nickel and copper and a large part of the iron and sulfur is obtained along with an acid slag almost free from copper and nickel. This slag may be granulated by a current of water, to facilitate its use as a component of mortar,'or it maybe poured into molds, to produce bricks, paving stones, drainage pipes and other building stone ware.

Second. The crude matte is roasted in such a manner that not only the copperbut also the nickel is for the greater part converted into sulfates, but the iron into the oxid. This result is obtained by keeping the temperature of roasting in the vicinity.

of 600 C.

Third. The copper and nickel sulfates obtained from the first or roasting operation are dissolved by leaching with acidulated water obtained from percolation towers through which the Waste gases from the roasting furnaces fiow in a counter stream toward the percolating water and therefore containing sulfurous and sulfuric acids.

Fourth. The residue from this leaching operation, consisting principally of iron oxid, but also containing an amount of imperfectly roasted or overroasted and therefore insoluble copper and nickel compounds,

is added as a. flux in the smelting operation first described. The insoluble copper and nickel is therefore reconverted into crude matte while the iron oxid owing to the oxidation of iron sulfid according to the equation:

Z,l-' e. ,O {I eS7FeO-iSO favors the oxidation of iron sulfids t0 ferrous oXid which enters into the slag thus leaving a matte richer in copper and nickel.

Fifth. By adding sulfid of calcium or sulfid of sodium to the acid solution obtained by the third operation copper is precipitated as a sulfid. After Separating the latter by filtration the nickel is precipitated from the filtered solution by adding more sulfid of calcium or sulfid of sodium. This is also to be separated from the solution by filtra-' tion. .The reactions involved in the foregoing are indicated in the following equatained as a slag.

Seventh. Since by the use of calcium sulfid as precipitating agent for copper and nickel trom the sulfate lyes too much gypsum is carried into the copper and nickel sulfid deposit, the calcium sulfid obtained from the sixth operation is turned into sul- 45 alone. The smelting of a sulfid ore to ob- 10 tions: fid of sodium by treating it, if necessary Na S H SO,=Na 'SO, H S under ressure with suitable sodium com- Q pounds, for example sodium sulfate in aque- 2 r- 2 4 ous solut1ons.- The sodium sulfid solution thus obtained may be used to better advan- N u 0 uS Na SO 15 a,2S+C S 4 C 2 tage as precipitating agent in the fifth op- Nags+NiSQ1=NiS+Na2SO4 eratlon. Sodmm sulfate solution 1s obtamed hereby whlch may again be regener- Sixth. The sulfids thus obtained are each ated to sodium sulfid solution by means of v (separately of course) reduced to copper calclum sulfid. 20 and nickel by smelting with a flux of llme- The followlng table Wlll give a still better stone and a carbonaceous reducing agent view on the whole process:

Ore- Resulting product.

Smelted with limestone or lixiviation residue in the electric furnacei l l Slag fgr malinghbriclks,

H101 31811 O' ers Crude matte products. ag

I Roasting to sulfates and lelachiug I I Lixiviatlon residue con- Solution containing the sisting of.iron oxid and largest part of the nickundecomposed nickel el and copper in the and copper sulfid and form of sulfates. other insoluble com- 1. Precipitation with pounds sodliumsilllfld I I Solution containing coppersulfld'smelt edwith dium sulfate and nickel limestone and charcoal sulfate I l 2. Precipitation with t I Copper. -So |iium sulffld Calciufn sulfid Sohition containing so Nickel sul fid smelted dium sulfate with limestone and charcpal I -i Nickel. Calcium sulfid decomposed by means of sodium sulfate solution givilng I i I G sum1(byproducto Sodium sulfid solution 1 Va None of the separate stages of which the the solution, the electric smelting of nickel 50 process is made up is novel when considered sulfid with limestone and charcoal to obtain metallic nickel, are all processes well known tain crude matte the roasting of the matte in electric-metallurgy. Similarly the subto form sulfates, the lixiviation of the products of roasting, the gradual precipitation of first the copper and then the nickel from in the precipitation to prevent the depositing of gypsum is not novel per se. It was stitution of calcium sulfid by sodium sulfid the residue.

not previously known however that from nickel ores poor in copper there could be extracted both these metals mentioned almost without any loss by smelting the ore to obtain a nickel copper matte, roasting the matte to sulfate, lixiviating the product of roasting, gradual precipitation by means of soluble sulfids and separate smelting of the sulfids. And this surprising result is obtained inspite of all the imperfections of the roasting and lixiviating processes by using the roasting and leached matte now chiefly consisting of iron oxid as flux in the first stage of smelting theore to anickel copper matte.

The following explanations should be noted. It is known that noroasting and lixiviating process in one operation will give a satlsfactory output of the metal. to be recovered. In the present process we obtain only 80 to 90% in the form of sulfate of the copper and nickel contained in the matte. The remaining 10 to 20% remain in The lixiviation residues could be subjected to a subsequent roasting and lixiviation as is done in the Ziervogel process at Mansfeld to extract the last traces of silver, but this would entail a considerable addition to the working costs. Owing however to the step of adding this residue to the ore to be smelted in the first stage an appreciable diminution-of the working costs is obtained which is explained as follows: The Fe O of the roasted and leached residue oxidizes the sulfids of the ore according to the equation are o resflreo so The first consequence of this reaction is that a larger amount of iron is converted into slag so that a matte richer in nickel and copper is obtained. Furthermore the addition of the roasted and leached residue to the ore charge introduces heat generating reactions into the smelting process. This will be seen from the formula and from the fact of the neutralizing action between FeO and SiO,, namely the conversion to slag of the FeO withthe silica of the acid gangue.

This is confirmed by the fact that in the l smelting tests carried out by the inventors,

less power was used when lye residues were added to the ore than when the ore alone was smelted, the quantity of ore treated being the same in both cases. The fluidity of the slag is increased by the inexpensive flux added. .That part of the copper and nickel contents of the ore which cannot be recovered by one roasting and one leaching operation is converted into crude matte and thus assists in rendering this latter richer in the above metals. In the smelting test very pure slags containingmostly less than 0.1% of nickel and copper were melted.

What we claim is 1. An improved process for the extraction of nickel and'copper from ores or byproducts containing the sulfids of these metals and.

of iron, consisting in the combination of the following operations: smelting the ore to a matte and a slag almost free from copper and nickel, roasting the matte at a temperature of about 600 C, leaching the sulfates by means of acidulated water, returning the residues from this leaching process to the first stage ofmatte smeltin precipitating from the sulfates solution rst the copper and then separately the nickel by means of alkaline sulfids, reducing each of the precipitated, filtered and dried sulfids of copper and of nickel separately by smelting with alkaline earth flux and carbonaceous agents, thus obtaining pure copper and pure nickel and a slag consisting chiefly of calcium sulfid, and utilizing the latter preferably after its conversion into sulfid of sodium as a precipitating agent for the copper and nickel sulfate solutions.

2. The process for extracting nickel and copper from ores and the like containing sulfids, which comprises smelting the ore to a matte and a slag almost free from said metals, roast-ing the matte at a temperature of approximately 600 C., leaching the roasted material with acidulated water, precipitating from the sulfate solution first the copper and .then the nickel by means of alkaline sulfids, and smelting the resulting sulfids of copper and nickel separately with a suitable flux. V

In testimony whereof weaflix our signatures in presence of two witnesses.

WILHELM BORCHERS. HABALD .PEDERSEN. 

